.base {
    width: 50px;
    height: 50px;
    background: url(../../Resource/img/p2.png) no-repeat center center;
    cursor: pointer;
    overflow: hidden;
    border: none;
    display: block;
    text-indent: -999em;
    margin: 6px;
}

.selected {
    composes: base;
    background: url(../../Resource/img/p1.png) no-repeat center center;
}